1. Field of the Invention
The present invention relates to an optical disk high-speed replaying/recording apparatus which replays an optical disk at a speed higher than a normal replay speed for reading data recorded on the optical disk, and records the read data on a writable/rewritable optical disk. More specifically, the present invention relates to a high-speed replaying/recording apparatus which replays an optical disk at a replay speed suitable for the optical disk.
2. Description of the Background Art
In recent years, there have been developments of optical disk high-speed replaying/recording apparatuses capable of reproducing data recorded on various types of optical disks typified by CDs and DVDs at a speed higher than the original replay speed and also recording the reproduced data on another writable/rewritable optical disk.
The operation of a typical example of the optical disk high-speed replaying/recording apparatuses in which a CD is used as a recording source optical disk and an MD is used as a writable/rewritable optical disk is briefly described below. The CD having recorded thereon music or non-music data is rotated at a speed higher than the normal replay speed. The recorded data is then read in units smaller than tracks. The read data is then written in the MD in predetermined recording units (data blocks smaller than reading units or tracks, or CDs).
Management information regarding this written data is written in a UTOC (User Table of Content) area of the MD, thereby achieving completion of recording of the data reproduced from the CD onto the MD. The management information written in this UTOC area is hereinafter referred to as UTOC information. The UTOC information can be written/rewritten by users in the UTOC area in accordance with the data writing state. On the other hand, as is well known, TOC (Table of Content) information cannot be arbitrarily written or rewritten by users in a TOC area provided on a read-only optical disk, such as a CD.
In the optical disk high-speed replaying/recording apparatus, data is read from a recording source optical disk (CD) by rotating the disk at a high speed obtained by increasing a normal replay speed several-fold. Therefore, in some cases, the recorded data cannot be correctly read from the CD due to replay inhibiting factors negligible at normal replay, such as, firstly, surface flaws or deformation of the CD; secondly, insertion accuracy; thirdly, circuit noise; and lastly combinations of those. Consequently, data cannot be correctly recorded in the MD. In such cases, even though the user desires high-speed replaying/recording, the replay speed has to be reduced to a speed at which data can be correctly read from the CD in order to record the data on the writable/rewritable optical disk.
Of the above replay inhibiting factors, physical defects of the medium, such as surface flaws or deformation of the CD, are not influenced by the replay speed itself. However, as the rotational speed, that is, the replay speed, of the CD is lower, the degree of inhibition regarding optical reading by an optical pickup is lower, and therefore data reading is improved. Also, positional accuracy, such as accuracy of insertion of the CD in the CD drive, is not influenced by the replay speed itself. However, as the rotational speed of the CD is lower, the degree of changes in positional relation between the optical pickup and a pit caused by errors in positional accuracy is lower, and therefore data reading is further improved. Furthermore, electrical inhibiting factors, such as circuit noise, are basically not influenced by the rotational speed of the CD, but are influenced by the replay speed as electrical processing. That is, as the replay speed is lower, influences of noise are smaller, and therefore data reproduction is improved.
In the above various replay inhibiting factors, the inability to normally reproduce the recorded data from the CD at high speed replay is a direct reason for the inability to normally record the data on the MD. Therefore, whatever the true reason for trouble in data reproduction is, the optical disk high-speed replaying/recording apparatus is structured so as to reduce the rotational speed, that is, the replay speed, of the CD for a recovery of normal reproduction of the recorded data, and then recording the reproduced data on the MD.
The CD, which is an example of the above-described recording source optical disk, is under CLV (Constant Linear Velocity) control so that the linear velocity is constant. That is, when a read position is at the inner rim side, the rotational speed is higher compared with a case where the read position is at the outer rim side. Also, depending on the types of the optical disks other than the CD, various rotation control schemes are used, such as a CAV (Constant Angular Velocity) scheme, a ZCAV (Zone Constant Angular Velocity) scheme, and a ZCLV (Zone Constant Linear Velocity) scheme. Therefore, the replay speed and the rotational speed of the optical disk do not have a fixed relation. Rather, depending on the read/replay position of the optical disk, the optical disk can be rotated at a different speed even with the same replay speed. However, the above control schemes are similar to each other in that the optical disk high-speed replaying/recording apparatus is structured to reduce the replay speed (rotational speed) when reading cannot be made, thereby waiting until reading of the recorded data is improved.
As described above, in the optical disk high-speed replaying/recording apparatus, depending on the read/replay position, the rotational speed of the optical disk is varied even with the same replay speed. Therefore, influences of the above three replay inhibiting factors are varied depending on the read/replay position. For example, consider a case where there is a data reproduction factor of a uniform size in the radial direction of the optical disk. In this case, when high-speed replaying/recording is performed at a constant replay speed, data reproduction can be successfully made in the outer rim, but can fail in the inner rim, or vice versa. Furthermore, the replay inhibiting factor can be varied in size, and also can be located in various places. Therefore, a sudden halt to replay or a sudden start of replay can occur during high-speed replaying/recording.
In the optical disk high-speed replaying/recording apparatus, every time the recorded data is read and reproduced from the CD, the data is actually recorded on the MD in sequence, and its UTOC information is written in units of tracks or CDs, thereby completing recording on the MD. Therefore, if reproduction defects occur in the course of recording data on the MD, depending on the timing of writing the UTOC information, defective data may be recorded on the MD at least in units of tracks or CDs. In that case, inconveniences may occur depending on the type of the recorded defective data or the location of the defective data, such as that the data which has been read from the CD and then recorded on the MD cannot be read in units of tracks or CDs.
In order to prevent such inconveniences, the following measure is required. That is, when replay abnormality occurs at a read position, the replay speed is reduced stepwise to an appropriate replay speed which allows normal replay at that read position, and then data reproduction is restarted at the reduced replay speed. The replay speed at the time of restarting high-speed replaying/recording is obtained by reducing a predetermined speed from the original replay speed of high-speed replaying/recording. In this sense, the replay speed at the time of restarting is hereinafter referred to as a reduced replay speed.
However, the read data units to be reproduced at the newly-found appropriately reduced replay speed from the read position where the replay abnormality occurred are different in replaying and recording conditions from other data units that have already been read and recorded on the MD. Therefore, consistency in the recorded data will be disadvantageously lost. In order to prevent such disadvantages, a read position from which data reproduction is restarted at the reduced replay speed has to be a predetermined number of read data units behind the position where replay abnormality occurred.
That is, it is practically meaningless to record each read data unit alone on the MD for reproduction. Instead, by recording a plurality of read data units on the MD in accordance with predetermined rules, a meaningful piece of record data unit is formed on the MD, and is utilized by users. In one example where the CD contains music tracks, a predetermined number of read data units are sequentially recorded on the MD in accordance with predetermined rules, thereby completing a piece of track data corresponding to one track. In another example where the CD contains computer data, a predetermined number of read data units are sequentially recorded on the MD in accordance with predetermined rules, thereby completing a piece of sector data. A collection of such pieces of sector data forms a file.
However, the read data units to be reproduced at the newly-found appropriate reduced replay speed from the read position where replay abnormality occurred are different in replaying and recording conditions from other data units that have been already read and recorded on the MD. Therefore, consistency in the recorded data will be disadvantageously lost. Consequently, further recording of such inconsistent data units to form a piece of track data on the MD makes it impossible to reproduce correct information from the track data.
In order to prevent such inconsistency in the recorded data units, reproducing is restarted at the reduced replay speed by going back to the read start position of the recorded data unit (track, file) to which the read data unit having defects belongs. That is, the read data unit that has been already reproduced at the original high-speed replay speed has to be redundantly reproduced under different conditions.
However, as described above, the replay inhibiting factor can be varied in size, and also can be located in various places. Therefore, a sudden halt to replay or a sudden start of replay can occur at high-speed replaying/recording. In other words, even when high-speed replay is started at a newly-set reduced replay speed, defects may occur before the completion of reproduction of the entire record units after only a few read data units are reproduced from the read position where reproduction defects occurred.
As such, frequent occurrences of read defects even at the reduced replay speed would increase redundant work loads in reproducing the already-reproduced data unit. These increased work loads significantly impair the high-speed replaying/recoding function, at which the optical disk high-speed replaying/recording apparatus is originally aimed. In worst cases, it takes more time compared with a case of replaying/recording the CD at its original normal speed.